Methods for making contact device for making connection to an electronic circuit device and methods of using the same

ABSTRACT

Improved contact devices and methods for producing contact devices and using such contact devices to produce electronic devices are disclosed. A contact device having a plurality of nominally coplanar first contact elements makes electrical contact with corresponding nominally coplanar second contact elements of an electronic device such an integrated circuit or liquid crystal or other display when the contact device and the electronic device are positioned so that the plane of the first contact elements is substantially parallel to the plane of the second contact elements and relative displacement of the devices is effected in a direction substantially perpendicular to the plane of the first contact elements and the plane of the second contact elements. The contact device preferably consists of a stiff substrate having a major portion with fingers projecting therefrom in cantilever fashion, each finger having a proximal end at which it is connected to the major portion of the substrate and an opposite distal end and there being one or two contact elements on the distal end of each finger.

BACKGROUND OF THE INVENTION

[0001] This invention relates to contact devices for making connectionto an electronic circuit device and to methods of fabricating and usingsuch a contact device, such as in the manufacture of semiconductor,liquid crystal displays or other devices, and improved contact devices.

[0002] An important aspect of the manufacture of integrated circuitchips is the testing of the circuit embodied in the chip in order toverify that it operates according to specifications. Although thecircuit could be tested after the chip has been packaged, the expenseinvolved in dicing the wafer and packaging the individual chips makes itpreferable to test the circuit as early as possible in the fabricationprocess, so that unnecessary efforts will not be expended on faultydevices. It is therefore desirable that the circuits be tested eitherimmediately after wafer fabrication is completed, and before separationinto dice, or after dicing, but before packaging. In either case, it isnecessary to make electrical connection to the circuits' externalconnection points (usually bonding pads) in a non-destructive way, so asnot to interfere with subsequent packaging and connection operations.

[0003] U.S. Pat. No. 5,221,895 discloses a probe for testing integratedcircuits. The probe includes a stiff metal substrate made of berylliumcopper alloy, for example. The substrate is generally triangular in formand has two edges that converge from a support area toward a generallyrectangular tip area. There is a layer of polyimide over one main faceof the substrate, and gold conductor runs are formed over the layer ofpolyimide. The conductor runs and the metal substrate form microstriptransmission lines. The conductor runs extend parallel to one anotherover the tip area and fan out toward the support area. A contact bump isdeposited on the end of each conductor run that is on the tip area. Thetip area of the substrate is slit between each two adjacent conductorruns whereby the tip area is divided into multiple separately flexiblefingers that project in cantilever fashion from the major portion of thesubstrate.

[0004] The probe shown in U.S. Pat. No. 5,221,895, is designed to beused in a test station. Such a test station may include four probeshaving the configuration shown in U.S. Pat. No. 5,221,895, the probesbeing arranged in an approximately horizontal orientation with theircontact bumps facing downwards, with the four rows of contact bumpsalong four edges of a rectangle. The DUT is generally rectangular andhas connection pads along the edges of one face. The DUT is placed in avacuum chuck with its connection pads upwards. The vacuum chuck drivesthe DUT upward into contact with the probe, and overdrives the DUT by apredetermined distance from first contact. According to current industrystandards, such a test station is designed to produce a nominal contactforce of 10 grams at each connection pad. Therefore, the amount of theoverdrive is calculated to be such that if contact is made at allconnection pads simultaneously, so that each contact bump is deflectedby the same amount, the total contact force will be 10 grams forcemultiplied by the number of connection pads.

[0005] If the material of the probe substrate is a beryllium copperalloy and each flexible finger has a length of about 0.75 mm, a width ofabout 62 microns and a height of about 250 microns, and the probe issupported so that the mechanical ground is at the root of the fingers,the contact force produced at the tip of the finger is about 7.7 gramsfor each micrometer of deflection of the tip of the finger. Therefore,if the contact bumps at the tips of the fingers are coplanar and theconnection pads of the DUT are coplanar, and the plane of the contactbumps is parallel to the plane of the connection pads, an overdrive ofabout 1.3 microns from first contact will result in the desired contactforce of 10 grams at each connection pad. However, if one of theconnection pads should be 1.3 microns farther from the plane of thecontact bumps than the other connection pads, when the DUT is displacedby 1.3 microns from first contact, there will be no contact forcebetween this connection pad and its contact bump, and all the contactforce that is generated will be consumed by the other contacts. If oneassumes that the contact force at a connection pad must be at least 50percent of the nominal contact force in order for there to be a reliableconnection, then the maximum variance from the nominal height that thisdesign will accommodate is +/−0.7 microns. However, the heightvariations of contact bumps and connection pads produced by the standardprocesses currently employed in the semiconductor industry typicallyexceed 5 microns.

[0006] Furthermore, even if the contact bumps are coplanar and theconnection pads are coplanar, tolerances in the probing apparatus makeit impossible to ensure that the plane of the connection pads isparallel to the plane of the contact bumps, and, in order to accommodatethese tolerances, it is necessary to displace the DUT by 75 microns inorder to ensure contact at all connection pads. If the dimensions of thefinger were changed to accommodate a displacement of 70-80 microns (75microns +/−5 microns), the probe would become much less robust. If theprobe were supported at a location further back from the root of thefingers, such that most of the deflection would be carried by thesubstrate rather than the fingers, the ability of the fingers to conformwould be limited to 0.13 microns/gram deflection produced at the fingersthemselves.

[0007] The connection pads of the DUT are not coplanar, nor are theconnection bumps on the probe. Assuming that the nominal plane of theconnection pads (the plane for which the sum of the squares of thedistances of the pads from the plane is a minimum) is parallel with thenominal plane of the contact bumps, the variation in distance betweenthe connection pad and the corresponding contact bump is up to 5 micronsif both the DUT and the probe are of good quality.

[0008] At present, the connection points on an integrated circuit chipare at a pitch of at least 150 microns, but it is expected that it willbe feasible for the pitch to be reduced to about 100 microns within afew years.

[0009] As the need arises to make connection at ever finer pitches, thestress in a probe of the kind shown in U.S. Pat. No. 5,221,895increases. If the connection pads are at a spacing of 75 microns, thisimplies that the width of the fingers must be less than about 50microns, and in order to keep the stress below the yield point, theheight of the fingers must be at least 400 microns.

[0010] The necessary height of the fingers can be reduced by employing ametal of which the yield point is higher than that of beryllium copper.For example, if the substrate is made of stainless steel, having anelastic modulus of 207×10⁹ N/m², the maximum height of the fingers canbe reduced to about 350 microns. However, it follows that the deflectionis reduced below that necessary to comply with typical height variationsfound in the industry. Additionally, the resistivity of stainless steelis substantially higher than that of beryllium copper, and this limitsthe frequency of the signals that can be propagated by the microstriptransmission lines without unacceptable degradation. In general, priortechniques found limited application due to difficulties in achievingadequate deflection with the necessary force to achieve reliableconnection, while withstanding the generated stresses.

[0011] In addition, although the microstrip transmission line hasadequate characteristics for signals up to a frequency of 5 GHz, and ithas been discovered that the so-called stripline configuration isdesirable for higher frequencies.

[0012] U.S. Pat. No. 5,621,333 and PCT/US96/07359, both of which areincorporated herein by reference, disclose improvements and advancementsover what is described in U.S. Pat. No. 5,221,895. It has beendiscovered, however, that further improvements and advancements oversuch disclosures, particularly with respect to the manufacture andstructure and use of such contact devices or probes, is required to makecontact devices over probes for fine pitch and other integratedcircuits, liquid crystal displays and other electronic devices.

SUMMARY OF THE INVENTION

[0013] The present invention provides improvements and advancements oversuch prior disclosures, particularly with respect to the manufacture andstructure and use of such contact devices or probes, is required to makecontact devices over probes for fine pitch and other integratedcircuits, liquid crystal displays and other electronic devices.

[0014] In accordance with a first aspect of such contact devices, theremay be provided a method of making a multilayer composite structure foruse in manufacture of a contact device for establishing electricalconnection to a circuit device, said method comprising providing asubstrate of a metal having a resistivity substantially greater thanabout 10 micro-ohm cm, adhering a first layer of metal having aresistivity less than about 3 micro-ohm cm to a main face of thesubstrate, the first layer having a main face that is remote from thesubstrate, adhering a second layer of dielectric material to the mainface of the first layer, the second layer having a main face that isremote from the substrate, and adhering a third layer of metal to themain face of the second layer, the metal of the third layer having aresistivity less than about 3 micro-ohm cm.

[0015] In accordance with another second aspect of such contact devices,there may be provided a method of making a contact device for use inestablishing electrical connection to a circuit device, said methodcomprising providing a substrate of a metal having a resistivitysubstantially greater than about 10 micro-ohm cm, the substrate having amajor portion and a tip portion projecting therefrom along an axis,adhering a first layer of metal having a resistivity less than about 3micro-ohm cm to a main face of the substrate, the first layer having amain face that is remote from the substrate, adhering a second layer ofdielectric material to the main face of the first layer, the secondlayer having a main face that is remote from the substrate, adhering athird layer of metal to the main face of the second layer, the metal ofthe third layer having a resistivity less than about 3 micro-ohm cm,selectively removing metal of the third layer to form discrete conductorruns extending over the tip portion parallel to said axis, while leavingportions of the second layer exposed between the conductor runs, wherebya multi-layer composite structure is formed, and slitting the tipportion of the composite structure parallel to said axis, wherebyfingers are formed that project from the major portion of the compositestructure in cantilever fashion and each of which supports at least oneconductor run.

[0016] In accordance with another aspect of such contact devices, theremay be provided a probe apparatus for use in testing an integratedcircuit embodied in an integrated circuit chip, said probe apparatuscomprising a support member having a generally planar datum surface, agenerally planar elastic probe member having a proximal end and a distalend, at least one attachment member attaching the probe member at itsproximal end to the support member with the probe member in contact withthe datum surface, at least one adjustment member effective between thesupport member and a location on the probe member that is between theproximal and distal ends thereof for urging the distal end of the probemember away from the support member, whereby the probe member undergoeselastic deflection.

[0017] In accordance with another aspect of such contact devices, theremay be provided a probe apparatus for use in testing an integratedcircuit embodied in an integrated circuit chip, said probe apparatuscomprising a support member having a bearing surface, a probe memberhaving a proximal end and a distal end and comprising a stiff substratehaving first and second opposite main faces and conductor runs extendingover the first main face of the substrate from the distal end of thesubstrate to the proximal end thereof, the conductor runs of the probemember being distributed over a connection region of the first main faceof the substrate in a first predetermined pattern, at least oneattachment member attaching the probe member to the support member withthe second main face of the probe member confronting the bearing surfaceof the support member, a circuit board comprising a substrate having amain face and conductor runs distributed over a connection region ofsaid main face of the circuit board in a second predetermined pattern, aflexible circuit comprising a flexible substrate having a main face andfirst and second connection regions, and conductor runs extendingbetween the first and second connection regions of the flexiblesubstrate and distributed over the first connection region in a patterncorresponding to said first pattern and distributed over the secondconnection region in a pattern corresponding to said second pattern, afirst attachment device attaching the flexible circuit to the supportmember with the first connection region of the flexible circuitconfronting the connection region of the probe member and the conductorruns of the flexible circuit in electrically conductive connection withrespective conductor runs of the probe member, and a second attachmentdevice attaching the flexible circuit to the circuit board with thesecond connection region of the flexible circuit confronting theconnection region of the circuit board and the conductor runs of theflexible circuit in electrically conductive connection with respectiveconductor runs of the circuit board.

[0018] In accordance with another aspect of such contact devices, theremay be provided a method of making a multilayer composite structure foruse in manufacture of a contact device for establishing electricalconnection to a circuit device, said method comprising providing asubstrate, adhering a first layer of dielectric material to a main faceof the substrate, the first layer having a main face that is remote fromthe substrate, and adhering a second layer of metal to the main face ofthe first layer, the metal of the second layer having a resistivity lessthan about 3 micro-ohm cm.

[0019] In accordance with another aspect of such contact devices, theremay be provided a method of making a contact device for use inestablishing electrical connection to a circuit device, said methodcomprising providing a substrate having a major portion and a tipportion projecting therefrom along an axis, adhering a first layer ofdielectric material to the main face of the substrate, the first layerhaving a main face that is remote from the substrate, adhering a secondlayer of metal to the main face of the first layer, the metal of thesecond layer having a resistivity less than about 3 micro-ohm cm,selectively removing metal of the second layer to form discreteconductor runs extending over the tip portion parallel to said axis,while leaving portions of the first layer exposed between the conductorruns, whereby a multilayer composite structure is formed, and slittingthe tip portion of the composite structure parallel to said axis,whereby fingers are formed that project from the major portion of thecomposite structure in cantilever fashion and each of which supports atleast one conductor run.

[0020] In accordance with another aspect of such contact devices, theremay be provided a contact device having a plurality of nominallycoplanar first contact elements for making electrical contact withcorresponding nominally coplanar second contact elements of anelectronic device by positioning the contact device and the electronicdevice so that the plane of the first contact elements is substantiallyparallel to the plane of the second contact elements and effectingrelative displacement of the devices in a direction substantiallyperpendicular to the plane of the first contact elements and the planeof the second contact elements to generate a contact force of at least fat each pair of corresponding first and second contact elements, whereinit is necessary to effect relative displacement of the devices by adistance d in said direction from first touchdown to last touchdown,said contact device comprising a stiff substrate having a major portionwith fingers projecting therefrom in cantilever fashion, each fingerhaving a proximal end at which it is connected to the major portion ofthe substrate and an opposite distal end and there being at least one,and no more than two, contact elements on the distal end of each finger,a support member to which the substrate is attached in a manner suchthat on applying force in said direction to the distal ends of thefingers, deflection occurs both in the fingers and in the major portionof the substrate, and means for effecting relative movement of thedevices in said direction, and wherein the substrate is dimensioned suchthat relative displacement of the devices in said direction by adistance d from first touchdown generates a reaction force at eachcontact element of about 0.1*f+/−0.1*f, and further relativedisplacement of the devices in said direction by a distance of about 75micron or 5*d beyond last touchdown generates a reaction force at eachcontact element of about 0.9*f+/−0.1*f.

[0021] In accordance with another aspect of such contact devices, theremay be provided a method for testing/manufacturing devices such asintegrated circuits or displays (such as LCD panels), which may includethe steps of carrying out a manufacturing process for the DUT, such as aplanar-type integrated circuit manufacturing process, positioning theDUT on a positioning device, such as a vacuum chuck (the DUT may be inwafer or die form, in the case of integrated circuits, etc.), effectingalignment of a contact device in accordance with the present inventionwith the DUT to the extent required for proper placement, effectingrelative movement of the DUT with respect to the contact device toestablish initial contact thereto (as determined electrically or by amechanical means), over-driving the relative movement to establishreliable electrical connection, wherein stresses are desirably sharedbetween the extended fingers of the contact device and the substrate ofthe contact device, applying test signals to the DUT and determiningwhether the DUT is defective or otherwise within or outside acceptablespecifications, recording whether the pass/fail condition of the DUT(which may include mechanical notation, such as inking the DUT ifdefective, etc., or by data recording), removing the DUT from thepositioning device, and packaging and assembling the DUT if acceptable.

[0022] With the present invention, devices with connection points offine pitch may be reliably tested and manufactured; and in particularimproved contact devices, improved methods of making contact devices,and improved methods of producing electronic devices may be obtained inaccordance with various preferred embodiments and aspects as describedelsewhere herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] For a better understanding of the invention and to show how thesame may be carried into effect, reference will now be made, by way ofexample, to the accompanying drawings in which:

[0024] FIGS. 1-5 illustrate various steps during fabrication of acontact device that may embody the present invention, FIGS. 1 and 4being plan views and FIGS. 2, 3 and 5 being sectional views;

[0025]FIG. 6 is a partial perspective view of a contact device that mayembody the invention;

[0026]FIG. 6A is a sectional view on the line VIA-VIA of FIG. 6;

[0027]FIG. 7 is a general view, partly in section, of a semiconductortester;

[0028]FIG. 8 is a plan view of a circuit board and mounting plate thatform part of the test head of the tester shown in FIG. 7;

[0029]FIG. 9 is an enlarged perspective view of the mounting plate andalso illustrates back-up blocks that are attached to the mounting plate;

[0030]FIGS. 9A, 9B, and 9C are sectional views illustrating the mannerin which the back-up blocks are attached to the mounting plate;

[0031]FIG. 10 is an enlarged view of a flexible circuit that is used toconnect the circuit board to the contact device;

[0032]FIGS. 11A and 11B are sectional views illustrating the manner inwhich the contact device and the flexible circuit are positionedrelative to the mounting block;

[0033]FIGS. 12A and 12B are sectional views illustrating the manner inwhich the mounting plate and the flexible circuit are positionedrelative to the circuit board

[0034]FIG. 13 illustrates a substrate with four exemplary probe membersfor purposes of explaining preferred embodiments of fabricationprocesses in accordance with the present invention;

[0035]FIG. 14 is a diagram illustrated a chuck used in fabricatingcontact devices in accordance with preferred embodiments of the presentinvention;

[0036]FIGS. 15A and 15B are diagrams illustrated laser cutting ofcontact devices in accordance with preferred embodiments of the presentinvention;

[0037]FIG. 16 is a diagram illustrating an embodiment of the presentinvention in which dynamic adjustment of the probe member in relation toa focused laser beam is provided;

[0038]FIGS. 17 and 18 illustrate probe members fabricated in accordancewith alternate preferred embodiments utilizing a two phase type lasercutting process;

[0039]FIG. 19 illustrates contact points or pads of an electronic devicein accordance with alternative embodiments of the present invention;

[0040] FIGS. 20 to 22 illustrate electronic devices and probe membershaving or utilizing probe members with multiple contacts per finger;

[0041]FIG. 23 is a diagram illustrating a portion of a probe memberhaving a controlled impedance region and a stubb region;

[0042]FIGS. 24A to 24C illustrate improved contact devices in which moreuniform scrub characteristics may be obtained;

[0043]FIGS. 25A to 25D illustrates fingers of a probe having multiplecontacts per finger and partial compliance slits formed in a back sideof the finger;

[0044]FIGS. 26A and 26B are diagrams illustrating an improved electronicdevice and contact design flow in accordance with certain preferredembodiments of the present invention;

[0045]FIGS. 27 and 28 illustrate a configuration of probe members toproduce a contact device for probing multiple electronic devices or anarray of contacts, and an exemplary use of such a contact device; and

[0046]FIG. 29 illustrates a probe member having external components orimpedances formed on the probe member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0047] The context for the present invention will be by way of thedisclosure in U.S. Pat. No. 5,621,333 and PCT/US96/07359, which areincorporated herein by reference. Thereafter, improvements andadvancements over such disclosures in accordance with the presentinvention, particularly with respect to the manufacture and structure ofsuch contact devices or probes, will be described. It is understood thatmethods and structure may be used for testing fine pitch and otherintegrated circuits, liquid crystal displays and other electronicdevices.

[0048]FIG. 1 illustrates a substrate 4 of elastic metal having an uppermain face 6 and a lower main face. In a preferred embodiment of theinvention, the substrate is stainless steel and is about 125 micronsthick. The substrate is generally triangular in form, having two edges 8that converge from a support area 10 toward a generally rectangular tiparea 12. The substrate is substantially mirror-image symmetrical about acentral axis 18.

[0049] Referring to FIG. 2, a thin film 14 of gold is deposited on theupper main face 6 of the substrate 4 by evaporation or sputtering. Thegold film may be augmented by plating if desired. An insulating materialsuch as polyimide is spun or sprayed onto the upper main face of thefilm 14 in the liquid phase and is then cured to form a layer 16 about25 microns thick.

[0050] A layer 20 of gold is deposited over the upper main face 22 ofthe layer 16 by evaporation or sputtering. The layer 20 is patternedusing conventional photolithographic techniques to form strips 26 thatextend parallel to the central axis 18 over the tip area 12 of the probeand fan out from the tip area over the triangular part of the substrate4 toward the support area 10 but which may be connected together at thesupport area. Each strip has a proximal end and a distal end relative tothe support area 10. Additional metal is then deposited over the stripsby plating. After the strips have been built up to the desiredthickness, which may be about 12 microns, a layer 30 of photomaskmaterial (FIG. 5) is deposited over the upper surface of the structureshown in FIGS. 3 and 4 and holes 32 are formed in that layer over thedistal end of each strip 26, as shown in portion (a) of FIG. 5. A hardcontact metal, such as nickel, is deposited into these holes (FIG. 5,portion (b)) by plating, and the photomask material is then removed(FIG. 5, portion (c)). The connections between the strips are removed byetching. In this manner, separate conductor runs are formed over thelayer 16, and each conductor run has a contact bump 34 over its distalend. The conductor runs are 50 microns wide and are at a spacing betweencenters of about 125 over the tip area.

[0051] Referring to FIG. 6, a cover layer 40 of polyimide is formed overthe conductor runs 26, over a region of the substrate that is to therear, i.e. toward the support area 10, of the rectangular tip area 12and a layer 44 of gold is deposited over the layer 40 by evaporation orsputtering. The layer 44 may be augmented by plating. The result of thefabrication steps described above is a multilayer structure thatcomprises the substrate 4, the gold film 14, the polyimide layer 16, thegold conductor runs 26, the polyimide layer 40, and the gold layer 44.

[0052] The tip area of the multilayer structure is then slit, wherebythe tip area is divided into multiple separately flexible fingers 48that project in cantilever fashion from the major portion of thestructure. A given finger of the substrate may carry the distal endportion of a single conductor run, or it may carry the distal endportions of two adjacent conductor runs. The slitting of the tip areamay be performed by ablation using a ultraviolet laser. The poor thermalconductivity of stainless steel is a favorable factor with regard to thelaser ablation process. The width of the kerf that is removed is about17 microns, so that the width of a finger is either about 108 microns orabout 233 microns. The length of each finger is about 1 mm.

[0053] The structure shown in FIG. 6 may be used as a contact device formaking electrical connection to contact pads of an electrical circuitdevice, such as an integrated circuit chip or a flat panel displaydevice. The nickel bumps 34 serve as probe elements for contacting theconnection pads of the circuit device. When the contact device is inuse, each nickel bump contacts a single connection pad of the circuitdevice. A bump 34 a that is to contact a ground pad of the circuitdevice may be connected to the substrate by means of vias 46 formed inholes in the layer 16 before depositing the layer 20. Multiple vias 46may be provided along the length of the conductor run 26 that ends atthe bump 34 a in order to ensure that the contact bump 34 a is firmlygrounded.

[0054] The configuration of the conductor runs and their spacing resultsin there being a stripline transmission line environment to the rear ofthe forward boundary of the layer 44, whereas there is a microstriptransmission line environment forward of the layer 44. Naturally, theslitting of the tip area results in degradation of the microstriptransmission line environment. In the case of the fingers being about 1mm long, the microstrip transmission line environment extends to a pointthat is about 2 mm from the contact bumps. However the degradation isnot so severe as to distort signals at frequencies below about 10 GHz toan unacceptable degree.

[0055] The structure shown in FIG. 6 may be used for probing a circuitdevice in a semiconductor tester, as will be described with reference toFIGS. 7-11.

[0056] Referring to FIG. 7, the tester comprises a prober 102 having aframe 102 a that serves as a mechanical ground. A device positioner 104having a vacuum chuck 106 is mounted within or as part of the prober102. The prober includes stepping motors (not shown) that act on thedevice positioner for translating the vacuum chuck relative to the frame102 a in two perpendicular horizontal directions (X and Y) andvertically (Z), and for rotating the vacuum chuck about a vertical axis.The vacuum chuck holds a device under test, or DUT, 108. FIG. 7illustrates the DUT 108 as a die that has previously been separated fromother dice of the wafer in which it was fabricated, but it will beappreciated that, with appropriate modifications, the apparatus could beused for testing a semiconductor device at the wafer stage. As shown inFIG. 7, the DUT 108 has contact pads 112.

[0057] The tester also comprises a test head 116 that can be docked tothe prober so that it is in a reliably reproducible position relative tothe prober frame 102 a. The test head 116 includes an essentially rigidcircuit board 122 (FIG. 8) that comprises an insulating substrate andconductor runs 126 exposed at the lower main face of the substrate. Vias(not shown) extend through the substrate and terminate at contact pads128 that are exposed at the upper main face of the substrate. Thecircuit board 122 is removably held in the test head by screws that passthrough holes 130 in the circuit board. When the test head 116 is dockedin the prober 102 and the circuit board 122 is installed in the testhead, the circuit board 122 is disposed horizontally and the contactpads 128 engage pogo pins 132, shown schematically in FIG. 7, by whichthe contact pads of the circuit board are connected to stimulus andresponse instruments (not shown), for purposes of conducting appropriatetests on the DUT.

[0058] A mounting plate 136 is secured to the circuit board 122. Themounting plate is positioned relative to the circuit board by guide pins134 that project downward from the mounting plate and entercorresponding holes in the circuit board. The manner in which themounting plate is attached to the circuit board will be described below.

[0059] The mounting plate has a generally cylindrical exterior surfaceof which the central axis 138 is considered to be the axis of the plate.The plate 136 is disposed with its axis 138 vertical and defines across-shaped through opening (FIG. 9) that is mirror image symmetricalabout X-Z and Y-Z planes that intersect at the axis 138. At the outerend of each limb of the cross, the plate 136 is formed with a notch 140that extends only part way through the plate and is bounded in thevertically downward direction by a horizontal surface 142.

[0060] A backup block 146 having the general shape, when viewed in plan,of a trapezoid seated on a rectangular base is positioned with itsrectangular base in one of the notches 140. Similar backup blocks 148are mounted in the other notches. The following description of thebackup block 146 and associated components applies equally to the backupblocks 148.

[0061] The rectangular base of the backup block 146 has a planarmounting surface 150 (FIG. 7) that can be seated against the horizontalsurface 142 at the bottom of the notch 140. For assembling the backupblock 146 to the mounting plate 136, the backup block is formed with ahole 152 extruding through its rectangular base, and the mounting plateis formed with a blind hole 156 that is parallel to the axis of themounting plate and enters the plate 136 at the horizontal surface 142. Aguide pin 160 is inserted through the hole 152 in the backup block andinto the blind hole 156 in the mounting plate, and in this manner thebackup block is positioned with a moderate degree of precision relativeto the mounting plate.

[0062] The backup block 146 is then attached to the mounting plate 136by a vertical locking screw 164 (FIG. 8, FIG. 9A) that passes through aclearance hole 168 in the backup block 146 and enters a threaded bore172 in the mounting plate 136 and a horizontal locking screw 176 (FIG.7) that passes through a clearance hole 180 in the mounting plate andenters a threaded bore 184 in the backup block. The backup block 146 isthereby attached to the mounting plate, and the guide pin 160 is thenremoved. The clearance holes 168 and 180 allow a small degree ofhorizontal and vertical movement of the backup block relative to themounting plate.

[0063] Two horizontal screws 186, which are horizontally spaced anddisposed one on each side of the screw 176, are inserted throughthreaded holes in the peripheral wall of the plate 136 and enter blindclearance holes in the backup block. Similarly, two vertical screws 190,which are horizontally spaced and disposed one on each side of the screw164, are inserted through threaded holes in the backup block 146 andengage the surface 142 of the mounting plate 136. The screws 176 and 186can be used to adjust the horizontal position of the backup blockrelative to the mounting plate 136. By selectively turning the screws176 and 186, the backup block can be advanced or retracted linearlyand/or rotated about a vertical axis. In similar fashion, using screws164 and 190, the backup block can be raised or lowered relative to themounting plate and/or tilted about a horizontal axis. When the backupblock is in the desired position and orientation, the locking screws aretightened.

[0064] The apparatus shown in FIGS. 7-10 also comprises a contact device194 associated with the backup block 146. The contact device 194 isgenerally triangular and has two edges that converge from a support areatoward a generally rectangular tip area. The tip area of the contactdevice is divided into multiple fingers that extend parallel to an axisof symmetry of the contact device. The contact device includes conductorruns that extend from the support area to the tip area, and one runextends along each finger in the tip area. At its support area, theconductor runs of the contact device are exposed on the underside of thecontact device. The contact device may be fabricated by the method thatis described above with reference to FIGS. 1-6.

[0065] Inboard of the rectangular base, the trapezoidal portion of thebackup block 146 extends downward toward the central axis 138. Thecontact device 194 is disposed below the inclined lower surface of thebackup block 146 and is positioned relative to the backup block by guidepins 202 (e.g., FIGS. 11A and 11B) that project from the backup blockand pass through alignment holes 204 in the contact device. The mannerin which the contact device is attached to the backup block will bedescribed below.

[0066] The apparatus also comprises a flexible circuit 208 having aninner edge region 208A and an outer edge region 208B (e.g., FIG. 10).The flexible circuit comprises a substrate of polyimide or similarinsulating material, a ground plane (not shown) on the lower side of thesubstrate, and multiple discrete conductor runs 210 on the upper side ofthe substrate. Over the inner edge region 208A, the spacing of theconductor runs 210 corresponds to the spacing of the conductor runsacross the support area of the contact device 194, and over the outeredge region 208B, the spacing of the conductor runs 210 corresponds tothe spacing of the conductor runs 126 along the inner edge of theprinted circuit board 122.

[0067] The flexible circuit is formed with inner and outer pairs ofalignment holes 214A and 214B. The inner pair of alignment holes 214Aare threaded by the guide pins 202, whereby the inner edge region 208Ais positioned relative to the contact device 194. Similarly, the outerpair of alignment holes 214B are threaded by the guide pins 134, wherebythe outer edge region 208B of the flexible circuit is positionedrelative to the printed circuit board. The flexible circuit is alsoformed with two sets of mounting holes 218A and 218B.

[0068] The support area of the contact device 194, the inner edge region208A of the flexible circuit, and a first length 222A of Shinetsu stripare clamped between the backup block and a clamping plate 226A by meansof screws 230A. The outer edge region 208B of the flexible circuit 208,the inner region of the printed circuit board 122, and a second length222B of Shinetsu strip are clamped between the mounting plate 136 and asecond clamping plate 226B by means of screws 230B. The positions of thealignment holes 214A and 214B relative to the conductor runs of theflexible circuit are such that the conductor runs 210 at the inner edgeregion 208A of the flexible circuit are in registration with theconductor runs 26 in the support area of the contact device, and theconductor runs 210 in the outer edge region 208B of the flexible circuitare in registration with the conductor runs 126 along the inner edge ofthe printed circuit board. The Shinetsu strip, the thickness of which isexaggerated in FIG. 7, is characterized by anisotropic electricalconductivity when compressed perpendicular to its length: itsconductivity is very good in directions perpendicular to its own planeand is very bad in directions parallel to its own plane and to itslength. Thus, the Shinetsu strip 222A connects the conductor runs 26 ofthe probe member 194 to respective conductor runs 210 of the flexiblecircuit 208, and the Shinetsu strip 222B connects the conductor runs 210of the flexible circuit 208 to respective conductor runs 126 of theprinted circuit board 122.

[0069] Tightening of the clamping screws compresses the Shinetsu strips,which then establish a good electrically conductive connection betweenthe conductor runs of the contact device and the conductor runs 126 ofthe printed circuit board 122, through the Shinetsu strips andrespective conductor runs of the flexible circuit 208.

[0070] As described with reference to FIGS. 1-6, the tip area of thecontact device 194 is divided into fingers, each of which has a contactrun that terminates in a contact bump. Since the tip area is spaced fromthe support area, at which the contact device is clamped to the backupblock, the tip area can be deflected away from the plane of theunderside of the backup block. Vertical adjustment screws 234 are fittedin respective threaded holes in the backup block 146. By appropriateadjustment of the screws 234, the contact device can be preloaded to acondition in which the contact device 194 is deflected downwardsrelative to the backup block 146, and by further adjustment of thescrews 234 the tip area can be forced downward, or permitted to rise, ortilted about the axis 18. It is important to note that the “mechanicalground” therefore extends to a location of the contact device that isbeyond the support area but does not extend as far as the lip area. Asdescribed more fully below, proper positioning of mechanical ground canenable stress sharing between the fingers of the contact device and thecontact device substrate, thereby enabling the contact device towithstand the stresses that result from applying force sufficient toensure reliable contact between the DUT and the contact device, giventhe irregularities that can be expected in actual devices/conditions.

[0071] When all four backup blocks are properly installed in themounting plate 136, the tip portions of the four contact devices extendalong four edges of a square and are positioned for making electricallyconductive contact to the contact pads of the device under test. Byobserving the DUT through the opening defined between the inner ends ofthe four backup blocks, the DUT can be positioned for contacting thecontact bumps when the DUT is raised by the positioning device.

[0072] When the DUT is raised relative to the test head, the contactpads of the DUT engage the contact bumps of the contact device. Afterinitial contact has been established (first touchdown), the DUT israised an initial 10-15 microns, which is sufficient to absorb anyexpected error in coplanarity of the contact bumps and contact pads andachieve last touchdown (each contact bump is in contact with itsrespective contact pad). The DUT is then raised by a further 75 microns.The spring rate of the fingers and the spring rate of the base region ofthe substrate, between the fingers and the support area, are such thatthe contact force exerted at each contact pad is at least 10 grams. Theinitial deflection of 10-15 microns is sufficient to provide a contactforce of about 2 grams at a single finger, whereas the furtherdeflection of 75 microns provides a contact force of N*10 grams, where Nis the number of fingers, or 10 grams per finger. By sharing thedeflection between the fingers and the base region of the substrate, ahigh degree of compliance may be achieved, allowing contact with all thecontact bumps, without sacrificing the contact force that is needed toachieve a reliable electrical contact between the contact bumps and thefingers.

[0073] The elastic nature of the metal of the substrate ensures thatwhen the DUT is brought into contact with the contact bumps, and isslightly over driven, deflection of the fingers provides a desirablescrubbing action and also supplies sufficient contact force forproviding a reliable pressure contact between the contact bump and theconnection pad of the DUT.

[0074] The film 14 of gold may serve as the ground plane, and thesubstrate 4, although conductive, may not contribute to the electricalperformance of the device, although this depends on the thickness andconstituent material of the substrate. In alternative embodiments, forexample, the substrate is of sufficient thickness so that it providessufficient conductivity to serve as the ground plane, or may consist ofberyllium copper, and thereby provide sufficient thickness to serve asthe ground plane, with or without gold film 14.

[0075] It is should be particularly emphasized how the present inventionachieves desirous stress load sharing between the fingers and thesubstrate. It has been determined that with available materials, to beof practical size and provide suitable compliance/deflection of thefingers (such as to accommodate deviations from coplanarity, etc.),stress loads induced in the fingers and the substrate should be balanced(i.e., maintained in an acceptable relative range, below the stresslimit of the material). Proper positioning of a mechanical groundbetween the ends of the fingers and the back extremity of the supportarea can enable controlled balancing of the relative stress loads, whilealso ensuring an adequate deflection of the fingers to achieve adequatecompliance. In preferred embodiments, the relative stress loads of thefingers and substrate are maintained/balanced in a ranges of about 0.7to 1.3, 0.8 to 1.2 or 0.9 to 1.1. Other ranges may be utilized, providedthat a desirable balance is maintained, while of meeting the conditionsof adequate deflection/compliance in the fingers, while staying withinthe stress limits of the constant materials.

[0076] In combination with the stress load balancing, it also has beendiscovered that, with available materials, the length of the fingers,controlled by the length of the slit and overall physical geometry,etc., can be chosen to give the desired finger deflection/compliance,such as a desired deflection of greater than about 5 microns, 10microns, 12, microns or 15 microns, in the case of, for example, 60-80or 75 microns, etc., of overdrive, while maintaining stress balancing asdescribed above, which can produce a probe element that producesreliable connection with the DUT while surviving the resulting stressloads, etc.

[0077] The present invention may be desirably applied to the testing andmanufacture of devices such as integrated circuits or displays (such asLCD panels). Initially, a manufacturing process for the DUT 108 isconducted, such as a planar-type integrated circuit manufacturingprocess. For display devices, an appropriate LCD or other manufacturingprocess is conducted. After such manufacturing, the DUT 108 ispositioned on a positioning device, such as vacuum chuck 106 of prober102 (the DUT may be in wafer or die form, in the case of integratedcircuits, etc.). The DUT 108 is aligned with contact device 194 to theextent required for proper placement. Thereafter, relative movement iseffected of the DUT 108 with respect to the contact device 194 toestablish initial contact therebetween (as determined electrically or bya known mechanical means). After initial contact, over-driving of therelative movement to a predetermined degree is conducted (such asdescribed above) to establish reliable electrical connection, whereinstresses are desirably shared between the extended fingers of thecontact device and the substrate of the contact device. Positioning of amechanical ground as in the present invention is particularly desirousin this regard. Thereafter, test signals are applied to the DUT 108 andit is electrically determined whether the DUT is defective or otherwisewithin or outside acceptable specifications. The pass/fail condition ofthe DUT may be recorded (which may include mechanical notation, such asinking the DUT if defective, etc., or by data recording). Stillthereafter, the DUT 108 may be removed from the positioning device. Ifthe device is acceptable, known packaging and assembling of the DUT maybe performed.

[0078] With the present invention, devices with connection points offine pitch may be reliably tested and manufactured.

[0079] Conventional laser or other cutting of contact devices such asdisclosed in U.S. Pat. No. 5,621,333, however, have been determined tobe inadequate for fine pitch or otherwise more optimal contact devices.The present invention particularly provides improved methods forproducing such contact devices.

[0080] An important process in the formation of the contact device iscutting, preferably with a laser, fingers in the contact structure (see.e.g., FIG. 6). In accordance with preferred embodiments of the presentinvention, improved laser cutting processes are provided, which will nowbe described with reference to FIGS. 13 to 15. With such improvedmethods and implements to be hereinafter described, improved lasercutting of probe members in accordance with the present invention may beachieved.

[0081]FIG. 13 illustrates substrate or wafer 300, having alignment flat302, on which is patterned (in this illustrative embodiment) fourquadrants of probe members 310 of a contact device. Some contact devicesmay, for example, only use two rows of contacts, and thus only twoportions need be cut for a complete probe. In such embodiments, fourprobe members 310 could be included on substrate 300 and cuttingperformed so as to produce two complete contact devices. The number ofprobe members per contact device, and the numbers of probe members persubstrate, may vary depending upon the particular application, althoughfour quadrant probe members 310 are illustrated for a conventional foursided integrated circuit or display, etc. Substrate 300 also preferablyincludes guide pin holes 308 and fiducials 304 (fiducials 304 are to becut with the laser, as will be described hereinafter). Substrate 300also preferably includes fiducials 305, which are preferably formed aspart of the photolithography steps that are used to produce substrate300, and which serve to provide a known positional reference forsubstrate 300 (and probe members 310) for the laser positional andmotion system. It also should be noted that probe members 310 are shownwith outline 314. In preferred embodiments, outline 314 is not providedas part of the photolithographic or other processes that producesubstrate 300, but instead are provided by cutting of the laser. Forillustrative purposes, outlines 314 are shown in FIG. 13.

[0082] Substrate 300 is cut by being fixedly positioned on chuck 332,illustrated in FIG. 14. Probe members 310 align on islands 336 of chuck332, the areas to be laser cut being positioned over openings, groovesor indentations 326. Chuck 332 is machined or tooled so that all lasercuts are over indentations 326 in order for laser cutting debris ordross to exit. Islands 336 of chuck 332 are provided with separatevacuum pull down hole 336 and vacuum grooves 322 in order to providepull down on probe member 310 at points near where laser cutting is tobe performed. It has been discovered that peripheral vacuum pull downonly does not enable fine slits to be cut as may be achieved with thepreferred embodiment of chuck 332.

[0083] It also should be noted that chuck 332 includes alignment flat340, a plurality of peripheral vacuum holes 324 connecting to manifold334, which is formed in the interior of chuck 332 and provides“plumbing” to route the vacuum to the peripheral vacuum holes 324 andisland vacuum holes 336, etc. Chuck 332 also preferably includesindentation 320, which serves to enable wafer 300 to be picked up fromchuck 332 with conventional wafer tongs or the like. Chuck 332 alsoincludes guide pin cutting holes 328 and guide pin holes 330. It shouldbe noted that guide pin cutting holes 328 are larger than guide pinholes 330. One guide pin cutting hole 328 is positioned next to a guidepin hole 330, with two such pairs illustrated for illustrative purposes(more than two guide pin cutting holes and more than two guide pin holescould be provided; e.g., three pairs or four pairs of such holes, etc.).Each guide pin cutting hole is shifted in the same direction, e.g., leftor right (left in FIG. 14), from the corresponding guide pin hole. Aswill be explained later, such a consistent shifting enables holes forguide pins to be more efficiently formed in substrate 300.

[0084] It also should be noted that chuck 332 may be formed of twopieces, the rectangular base portion, and the rounded top portion. Thebase portion could be formed in a manner to be common to a variety oftop portions, while particular top portions may be produced to be usedwith one or more than one particular probe members to be laser cut. Withsuch a two piece chuck, the rectangular base portion may be used formore than top portion, thereby obviating the need for machining of thebase portion for each top portion. A particular top portion may besecured to the base portion by suitable guide pins or small profilescrews or the like in such a manner that top portions are secured to thebase portion in a physical position so as to line up in a correspondingmanner with plumbing or manifold ports in the base portion, so that adesirable vacuum may be applied to the substrate by way of the topportion.

[0085] Laser cutting is more optimally performed in accordance withembodiments of the present invention as follows. Substrate 300 isinitially produced to have probe members with conductors of the desirednumber, position and shape, such as described previously. Substrate 300is positioned on chuck 332, preferably with the circuit side facing thedirection of the laser beam; chuck 332 is positioned on, or a part of,the laser positioning and motion system, in a predetermined manner. Theoptical system of the laser may automatically or manually be used tolocate a position of a known feature on substrate 300, such as fiducials305 or the conductors formed as part of probe members 310. The laserpositional and motion system may thus have a predetermined positionalreference to both chuck 332 and substrate 300. It also should be notedthat data determinative of the features of substrate 300, which mayinclude fiducials 305, the conductor runs of probe members 310 and/orthe tracks where laser cutting is to be performed, preferably isprovided in the form of a data file, such as a DXF (design exchangeformat) or other suitable data file, preferably created as a part of theprocess that produced substrate 300.

[0086] With positional references known, fiducials 304 may be cut withthe laser. Laser cut fiducials 304 are used in order to conduct the mainlaser cutting with the circuit or conductor run side of substrate 300facing away from the laser beam. Such cutting from the back side hasbeen determined to produce more optimal cutting of the fingers of thecontact device.

[0087] Before or after fiducials 304 are formed, guide pin holes 308also are formed by laser cutting. With the conductor run side ofsubstrate 300 facing the direction of the laser beam, guide pin holes308 overlay guide pin cutting holes 328 of chuck 332. The ultimateposition of guide pin holes 308 vis-a-vis guide pin holes 330 of chuck332, illustrated by dotted line holes 306, will correspond in a desiredmanner when substrate 300 is flipped over and re-positioned on chuck332. As previously expanded, with the guide pin cutting holes offsetfrom the guide pin holes in a consistent directional manner, guide pinholes 308 may be laser cut with the conductor run side of substrate 300facing the laser beam direction (and with guide pin holes 308 ofsubstrate 300 overlying guide pin cutting holes 328 of chuck 332), andthereafter substrate 300 may be flipped over and repositioned on chuck332 so that guide pin holes 308 of substrate 300 overlay guide pin holes330 of chuck 332, and thus the position of substrate 300, with theconductor run side now facing away from the direction of the laser beam,may be secured on chuck 332 in a predetermined manner with guide pins.It should be noted that one of guide pin holes 308 of substrate 300 ispreferably formed as a slightly elongated hole or slot. This will enablesome minimal movement of substrate 300 vis-a-vis chuck 332 in order toaccommodate thermal coefficient of expansion mismatches between thechuck 332 and substrate 300.

[0088] As previously described, DXF or other suitable data filespreferably are provided to the laser positional and motion system. Withsubstrate 300 positioned on chuck 332, conductor run side facing awayfrom the direction of the laser beam, laser cutting may proceed. Itshould be noted that fiducials 304 previously cut with the laser arevisible to the laser optical system when substrate 300 is positioned onchuck 332 with the conductor runs facing away from the direction of thelaser beam, thereby serving as an automatic or manual aid to thealignment of the laser positional and motion system to the desiredcutting tracks on substrate 300. With the laser cutting tracks input bya suitable data file to the laser system, the laser may desirably cutthe fingers and outline of probe members 310 in a more accurate andoptimum manner.

[0089] Preferred methods of cutting the fingers and outlines of probemembers 310 will now be described with reference to FIGS. 15A and 15B.FIG. 15A illustrates a preferred area map for laser cutting of oneillustrative probe member 346. The laser preferably cuts “stitched”perimeter cuts 341, with some material 340 remaining between stitch cuts341. Stitch cuts 341 generally define the outline of probe member 346,with material remaining in order to provide support to probe member 346during the remaining laser cutting processes. It should be noted thatall laser cutting of probe member 346 preferably overlays open areas orindentations 326 on chuck 332, as previously described.

[0090] In the conductor run tip portion of probe member 346, area 342 iscut in order to provide a suitable laser track for cutting the fingersof probe member 346, as will be explained further hereinafter. Inaddition, guide pin holes 312 also are preferably cut in probe member346, with guide pin holes 312 (one of which preferably is elongated),available to serve as physical positional references for probe member346 in a final contact device (assuming that the final contact device ismechanically constructed to take advantage of such guide pin holes). Thepositional location of guide pin holes 312 preferably is provided by thesame data file that provides the positional data for the laser cuttingtracks.

[0091]FIG. 15B illustrates preferred embodiments of laser cuttingmethods in accordance with the present invention. A plurality of lasercutting tracks 345 are illustrated. Preferably, the laser is directed atfirst end 344A of a laser track 345, which is positioned in the openarea 342 previously cut by the laser. This enables the early laserpulses, which may be less stable, to be directed at an open area and notat the sensitive finger portion of probe member 346. Thereafter, thelaser positioning and motion systems steps the laser towards second end344B of the laser track. Preferably, laser cutting along tracks 345proceeds from first 344A to second end 344B, but not in the oppositedirection. It has been determined that a cut from end 344A to 344B and areturn cut from 344B to 344A may impart an excess of laser energy at theportion of the laser track at end 344B, which may result in an enlargedor “keyhole” type opening at end 344B, which may undesirably weaken thefinger portion of probe member 346 at this location. Alternatively, suchreturn cuts may be performed with a return cut from end 344B to end344A, but with the laser energy (either pulse rate or energy density)reduced near end 344B to avoid an enlarged keyhole type opening. Lasercutting from 344A to 344B proceeds until the entire thickness ofsubstrate 300 is traversed.

[0092] In certain preferred embodiments, each of the fingers of the tipportion of probe member 346 is cut with the laser until the cut is allof the way through the material of substrate 300. In other preferredembodiments, a single pass (or other predetermined number of passes)from 344A to 344B for a finger is made and then stepped to the adjacentfinger along the length of the tip portion. Without being bound bytheory, stepping from finger to finger may allow heat to dissipate moreoptimally as compared to repeated cutting on the same finger until thecut is complete.

[0093] It should be noted that chuck 332 in conjunction with substrate300 may be advantageously utilized in accordance with embodiments of thepresent invention to produce suitably fine and accurate slitting forprobe members. Chuck 332 serves to provide a desirous pull down vacuumclose, such as within 0.030 inches, to where most of the laser cuttingoccurs, while enabling laser cutting to occur over open indentations 326of chuck 332. This enables the material of substrate 300 to bemaintained in a more desirous flat condition on chuck 332 during lasercutting with vacuum pull-down, while allowing dross and debris of thelaser cutting to fall into an open area of chuck 332. It also should benoted that the machining to produce chuck 332 may desirably be conductedby a CAD/CAM system, with the positional and other reference data forthe CAD/CAM system for producing chuck 332 generated as a part of, or inan automated step subsequent to, the design process that created thedata for probe members 310 of substrate 300.

[0094] Also in accordance with preferred embodiments of the presentinvention, lasers are used with particular properties that have beendetermined to be particularly useful for making contact devices asdisclosed herein. In accordance with such preferred embodiments, thelaser is selected and controlled to provide energy of a wavelength lessthan about 400 nm. While YAG lasers have been applied in a variety ofapplications, it has been determined that a Nd:YAG laser operating atthe fourth harmonic, or about 266 nm, provides particularly goodresults, particularly when applied with a pulse duration of less than,or about 25 nanoseconds, and preferably between about 15-25 nanoseconds,with energy per pulse of about 200 microjoules, at a laser pulse rate ofabout 1000 Hz, or between 500 and 2000 Hz, or between 750 and 1500 Hz,and more preferably between 800 and 1200 Hz. With materials and otherparameters selected in accordance with embodiments of the presentinvention, a cutting velocity of about 5 mm/second has been determinedto provide desirable results.

[0095] Additional laser cutting parameters and methodologies determinedto be particularly advantageous in accordance with additional preferredembodiments of the present invention will now be described.

[0096] As for wavelength, wavelengths shorter than 400 nm have beendetermined to be preferable in such certain preferred embodiments.Longer wavelengths have been determined to in general produce moreburning and less ablation. In addition, the heat affected zone (HAZ)tends to be larger to the point of damaging material necessary for theprobe mechanical properties and electrical properties to perform in thedesired manner. On the other hand, wavelengths much longer than 200 nmalso may be undesirable. Shorter wavelengths are believed to typicallynot contain enough energy to do the necessary ablation in order toproduce slitting.

[0097] As for pulse width, in such certain preferred embodiments pulsewidths are controlled to be shorter than 30 nanoseconds. Longer pulsewidths tend to either contain more energy than the material candissipate and negatively affect the HAZ, or if the energy is reduced,there may be insufficient peak power to cause ablation. Pulse widthslonger than 5 nanoseconds are preferably used in such embodiments.Shorter pulse widths typically do not contain enough energy to causeablation, or ablate at such a slow rate as to become inefficient.

[0098] As for velocity, velocities faster than ¼ of the laser beamdiameter per pulse is preferably used in such embodiments. Slowervelocities tend to increase the energy absorbed per unit area to thepoint that the HAZ becomes large enough to negatively impact themechanical and electrical properties of the probe member. Velocitiespreferably are controlled to be slower than 1 beam diameter per pulse.Faster pulse rates are believed to leave material between pulse hitsthat do not see energy and do not produce proper slit formation.

[0099] As for energy per pulse, in such embodiments the energy per pulsepreferably is more than about 25 micro-joules. Lower energies per pulseare believed not to contain enough energy to cause sufficient ablationfor effective slit production. In such embodiments, the energy per pulsepreferably is controlled to be less than 300 micro-joules. Higherenergies tend to not be absorbed by the material without increasing theHAZ so that it becomes large enough to negatively impact the mechanicaland electrical properties of the probe member.

[0100] As for pulse rate, in such embodiments the pulse rate preferablyis controlled to be faster than 500 Hertz. Slower pulse rates have beendetermined to reduce the production rate of the laser system to thepoint that the slitting process becomes overly expensive. On the otherhand, in such embodiments that pulse rate preferably also is controlledto be slower than 2000 Hertz. Faster pulse rates are believed to eithernot contain enough energy per pulse to effectively ablate material orthey exceed the material's capacity to remove heat to the point that theHAZ becomes large enough to negatively impact the mechanical andelectrical properties of the probe member.

[0101] In accordance with preferred embodiments of the presentinvention, slit width also may be desirably controlled. In suchpreferred embodiments, the maximum slit width is controlled to be about10 microns, as wider slit widths have been determined to consumesignificant area and limit the pitch of the probe member toapproximately 100 microns due the need for area to allow for HAZ,position errors, signal path, etc. On the other hand, in such preferredembodiments the minimum slit width is controlled to be about 1 micron.Narrower slit widths have been determined to cause increased risk ofundesirable bridging and mechanical crosstalk due to contact betweenadjacent probe fingers.

[0102] An additional improvement to laser cutting methodologies inaccordance with certain preferred embodiments of the present inventionwill be described with reference to FIG. 16.

[0103]FIG. 16 illustrates laser beam 360 being directed onto probemember 354, such as for cutting slits between finger, such as describedelsewhere herein. In this embodiment, probe member 354 is positioned onchuck 352, which is positioned on elevation mechanism 350, which may beconsidered a “Z dimension” stage. Laser beam 360 is focused more towardsa point by lens 358 to produce focused beam 356. With the minimum spotsize in general being a fixed length from lens 358, in this embodiment acutting pass (or passes) is made in a particular area of probe member354. As the cut becomes deeper, elevation mechanism 350 adjusts chuck352 and probe member 354 upwards. As a result of the upward movement ofprobe member 354, the material that is to be cut by a subsequent pass offocused laser beam 356 may once again be with a more minimal beam size.Without such upward movement, the beam becomes in effect over-focused asthe cut becomes deeper, leading to a less focused and undesirably widerspot size, which makes it difficult to achieve fine slitting.

[0104] With such embodiments, the laser beam is more focused into a spotsuch that the energy density is high enough to change the material ofthe probe member into a form in which it is removed from the probemember, leaving the desired material intact. As the beam spot size is asignificant contributor to the kerf width of the material removed,dynamically adjusting the position of the probe member to maintain amore focused beam at the point of beam impact can significantly reducethe kerf width. In other embodiments, the position of the probe memberis maintained constant, while the position of lens 358 is adjusted. Whatis important is that the relative position of lens 358 and probe member354 is adjusted (dynamically) during a cutting pass, or between cuttingpasses, so that only a highly focused and small laser beam spot impingesupon the material to be removed.

[0105] Additional improvements and advantages of contact devices andprobes in accordance with embodiments of the present invention will nowbe described.

[0106] Referring now to FIGS. 17 and 18, certain additional preferredembodiments of laser cutting in accordance with the present inventionwill now be described. As illustrated in FIG. 17, laser cutting may beperformed in two phases, each of which may be conducted in one or moreseparate passes. Two fingers of probe member 370 are illustrated fordiscussion purposes. Each finger of probe member 370 includes conductivelower layer 371, on which is formed dielectric layer 372 and conductorruns 375 having contact bumps 374. The structure of and method offorming the fingers of probe member 370 may be as described elsewhereherein.

[0107] In this embodiment, laser cutting is first conducted from theback side of probe member 370, or the side opposite the side on whichconductor runs 375 are formed. Laser cutting proceeds with one or morepasses with a less controlled width, such as width X₂ as illustrated.The laser cutting of this phase may be a rougher, higher energy andperhaps faster cut phase. With the cutting being conducted from the backside, control of the cut is less important. The cutting of this firstphase goes to a depth less than the thickness of conductive lower layer371, which be achieved by way of measuring the depth of the cut or byexperimentation with particular laser parameters and materials. What isimportant is that the first phase of laser cutting be conducted from theback side of probe member 370 and not completely cut through the finger.

[0108] In a second phase, the laser cutting is now conducted from thefront side of probe member 370 (or the side on which conductor runs 375are formed), with a highly focused, high energy and relatively smallbeam spot. Preferably, the cutting from the front side of probe member370 is achieved with a side pass that completes the cutting through theprobe member. Preferably, the front side cut has a smaller width,illustrated as width X₁. With the cutting from the front side occurringin a single or very few passes, the amount of debris or dross depositingon the front side of probe member 370 may be minimized.

[0109]FIG. 18 illustrates a refinement of the two step laser cuttingapproach discussed in connection with FIG. 17. In the embodiment of FIG.18, probe member 373 includes layer 376 formed on conductive lower layer371. Dielectric layer 372 is formed on layer 376, and conductor runs 375having contact bumps 374 are formed on dielectric layer 372. Theconstituent materials of layer 376 are selected based on the particularlaser that is selected for the cutting operation. Layer 376 preferablyis highly reflective or otherwise non-absorbing of the lager beam, andserves as an “etch stop” or inhibiting layer to ensure that the firstphase, back side laser cutting does not cut entirely through probemember 373. In the second phase laser cutting, again conducted from thefront side of probe member 373, the laser cutting is again conductedwith a highly focused, high energy and relatively small beam spot.Preferably, the cutting from the front side of probe member 370 isachieved with a single pass that completes the cutting through the probemember. Preferably, the front side cut has a smaller width than the backside cut, as discussed in connection with FIG. 17. The front side cutmay be conducted with a laser beam of different parameters in order tomore readily remove the material of layer 376, etc. As before, with thecutting from the front side occurring all in a single or very fewpasses, the amount of debris or dross depositing on the front side ofprobe member 373 may be minimized.

[0110] Probe members in accordance with the present invention may beformed with very small width and fine pitch. As a result, improvedcontact probe structures may be achieved.

[0111] Referring to FIG. 19, a portion of electronic device 380 isillustrated having contact pads 382 and 384. Preferably electronicdevice 380 has contact pads of two different sizes, illustrated asdimensions Y₁ and Y₂. Due to the ability to make very fine pitchdevices, such as devices with fingers on a 40 or below 40 micron pitch,with slits of about 2 or about 1-3 microns, it is possible to haveadditional test only contact pads positioned on electronic device 380that are small and consume little surface area. Larger contact pads suchas pads 382 also may be probed with the contact device, with the largercontact pads also serving as bonding pads (the larger area of pads 382provide sufficient area for wire or other bonding in the devicepackaging process). Smaller pads 384 are provided only for testingpurposes and may be of a size not suitable for serving as a bonding pad.Such additional probe-test-only pads, more test contact points may beprovided, which may serve to provide parallel or otherwise moreefficient testing of electronic device 380.

[0112] Referring now to FIGS. 20 and 21, additional embodiments of thepresent invention will be described. As illustrated, electronic device397, which may be a high density memory device such as a 64M DRAM, isprovided to have two rows of bonding or contact pads 399 positioned in acenter portion of electronic device 397. Such a device structure may bewhat is known as a lead-on-chip (or LOC) configuration, with a leadframe (not expressly shown) secured to a front face of electronic device397 with, for example, an insulative adhesive, with bonding wiresextending from pads 399 to connection points of the lead frame.

[0113] In wafer probing of such a device, as illustrated in FIG. 20,fingers 390 of the contact device may include two contact bumps, frontbump 392 and back bump 394, and two conductor runs 396 and 398. Asillustrated, conductor runs 396 and 398 proceed substantially inparallel down the length of finger 390, with conductor run 396 extendingaround back contact bump 394 in order to make electrical contact tocontact bump 392. With such a contact device structure, a single fingermay contact a pair of the contact pads illustrated in FIG. 21. It ispossible to extend this concept to three, four or more contacts andconductor runs per finger, with the contacts three in a row, or atwo-by-two array, etc.

[0114] In addition, contact devices of this structure may be extended toprobing multiple electronic devices 397 with a single contact device391, as illustrated in FIG. 22. As illustrated, contact device 391 has aplurality of fingers 390 arranged in a manner to contact multipleelectronic devices 397. As with the contact device of FIG. 20, ifelectronic devices 397 include two rows of contact pads 399, thenfingers 390 may include two contact bumps. In such a manner, a singlecontact device 391 may be used to wafer probe a plurality (e.g., 4, 8,16, etc.) of electronic devices 397. It should be understood that theembodiment of FIG. 22 may include the ability to wafer test electronicdevices 397 having a single row of contact pads 399, or two rows ofcontact pads 399 (such as illustrated in FIG. 21), or three or four rowsof contact pads 399, with fingers 390 having a suitable correspondingnumber of contact pads and conductor runs. Still alternatively, twocontact devices may be provided to probe devices 397 from oppositesides, with each contact device probing one, two, three, four, etc. rowsof contact pads on the electronic devices.

[0115] Referring now to FIG. 23, an improved structure of a contactdevice of fine pitch will now be described. As illustrated, a portion ofcontact device 400 includes a plurality of fingers 402, on which areformed conductor runs 404, each of which has a contact bump 406 formedon a contact end thereof. Contact device 400 may be formed in a manneras described elsewhere herein. In this preferred embodiment, contactdevice 400 is formed to have at least two distinct regions, controlledimpedance region 410 and stub region 408.

[0116] Unlike conventional approaches in which it is desired to maintaina controlled impedance to the contact point for optimum signalpropagation characteristics, this embodiment compromises the signalpropagation characteristics in stubb region 408, while maintaining adesired controlled impedance in controlled impedance region 410. As anillustrative example, the controlled impedance may be desirably 50 ohms.Controlling the 50 ohm signal environment the entire length of fingers402, however, will impose a limit on how fine a pitch may be achieved.Deviating from the 50 ohm environment in stubb region 408 may enablemore area for slitting between fingers 402 as illustrated, therebyenabling finer pitch contact devices.

[0117] It should be noted that stubb region 408 desirably is limited tosubstantially less than the wavelength of any signals of interest. Forexample, the length of stubb region 408 should be less than about ¼ or ⅛of the wavelength of the highest frequency signals of interest, and morepreferably less than about {fraction (1/10)} of the wavelength of thehighest frequency signals of interest. As illustrated, with theconductor run narrowed only in the limited length of the stubb region(e.g., about 0.050 inches or less), fine pitch contact devices withsuitable frequency transmission characteristics may be desirablyachieved.

[0118] It should be noted that the embodiment of FIG. 23 may be appliedto both microstrip or stripline configurations.

[0119] Still further improved contact device structures in accordancewith other preferred embodiments of the present invention will bedescribed with reference to FIGS. 24A to 24C.

[0120] It has been determined that certain contact devices exhibitnon-uniform scrub characteristics. As a for example, certain contactdevices tend to exhibit less scrub for the fingers at the ends of therow of fingers. It in general is desirable to have more uniform scrubcharacteristics for all of the fingers of the row of fingers.

[0121] In FIG. 24A, a contact device having non-uniform slit lengths isprovided. As illustrated, contact device 412, which preferably includesmechanical ground 414 such as previously described, includes a pluralityof fingers in the tip region 416. As illustrated, fingers near the endof the rows of fingers have a different slit length from slits betweenfingers in the center portion of the row of fingers. Preferably, fingersnear the end of the row have a slit, such as slit 418, that is shorterthan the slits between fingers in the center portion, such as slit 420.With slits near the end of the row of a different (preferably shorter)length, a more uniform scrub characteristic may be obtained in certainembodiments.

[0122] In FIG. 24B, a contact device having a varying or non-uniformmechanical ground 424 is provided. As illustrated, contact device 422includes mechanical ground 424 with extending portions near the endregion 430 adjacent to the end of the row of fingers. In thisembodiment, fingers 428 in the tip region 426 of contact device 422 maybe of the same length, while a non-uniform mechanical ground alters thestress sharing characteristics of the fingers near the end of the row offingers as compared to fingers in the center portion of the row offingers. Preferably, mechanical ground 424 provides a mechanical groundcontact point nearer the base of fingers 428 for those fingers locatednear the end of the row of fingers. Still preferably, the mechanicalground may be provided in a manner to gradually vary from the end region430 of mechanical ground 424 to a center portion of the mechanicalground. With a varying or non-uniform mechanical ground, a more uniformscrub characteristic may be obtained in certain embodiments.

[0123] In FIG. 24C, a contact device having a varying or non-uniformfinger width is provided. As illustrated, contact device 432 includesmechanical ground 434 and a plurality of fingers (e.g., fingers 436 and438). Fingers near the end of the row of fingers (e.g., finger 436) isof a width greater than a finger near the center portion of the row offingers (e.g., finger 438). With a varying or non-uniform finger width,a more uniform scrub characteristic may be obtained in certainembodiments.

[0124] Further improved contact probe structures in accordance withadditional preferred embodiments of the present invention will now bedescribed with reference to FIGS. 25A to 25D. As illustrated in theseembodiments, two (and perhaps more than two) contact bumps 446 andconductor runs 444 are provided for each finger 441. Conductor runs 444are provided on dielectric 442, which is formed on conductor layer 440,such as in a manner described elsewhere herein.

[0125] In the illustrated embodiments, one or more partial slits 448 areprovided in the back side opposite the side where conductor runs 444 areformed. When multiple conductor runs are formed on a single finger, thefingers, being torsionally stiff, may not be sufficiently compliant toaccommodate height variations that may be encountered between contactpads of the electronic device to be tested. Through micromachining suchas with a laser, partial slits may be formed in the back side of thefingers to increase the torsional compliance.

[0126]FIG. 25A illustrates compliance slit 448 extending substantiallyin parallel to the length of finger 441. The arrow indicates a torsionalmoment created during an exemplary non-uniform contact. FIG. 25Billustrates compliance slit 448 having two portions, each extending froma center portion of the end of finger 441 to a point along the length offinger 441. FIG. 25C illustrates compliance slit 448 having two curvedportions, each extending from a center portion of the end of finger 441to a point along the length of finger 441. FIG. 25D illustratescompliance slit 448 extending initially in parallel to the length offinger 441 for a predetermined length, and then perpendicularly to thelength of finger 441 in the shape of a “T.” With such compliance slits,a contact device with two or more contact bumps and conductor runs perfinger with improved compliance may be obtained.

[0127] Still other improved methods of producing contact devices, andimproved methods of producing electronic devices using such contactdevices, will now be described.

[0128] In accordance with contact devices as described elsewhere herein,and also with techniques known as probe cards, using fine needles orwires, membrane contact devices utilizing a membrane having conductorsand connection points on a membrane which typically is pulled down overan elastomer (e.g., a truncated pyramid) (such as produced by CascadeMicrotech Inc.) and then contacted with the DUT and other contactdevices such contacts appended to microsprings/bonding wires (such asproduced by Formfactor, Inc.), construction of such contact devicestypically has been way of separate construction based on physical dataprovided in physical form (e.g., written or electronic numbers such asphysical coordinates, etc.), which are then using to construct thecontact device. Such a manner of manufacturing contact devices hasdisadvantages, such as requiring excessive manual intervention, forexample manual entry of contact location and the like into a tool formachining or otherwise fabricating the contact device. Such techniquesare inefficient to some degree and enable the introduction of errors andthe like, and improved methods are desirable for both the end devicemanufacturer and the manufacturer of the contact device. In addition,many such conventional techniques have been limited in that theconductors for the contact device are offered in a single or limited setof electrical characteristics (e.g., all needles having in effect thesame size and overall electrical characteristics, etc.), when in realityconductors for the contact device more desirably would have electricalor physical characteristics more correspondingly optimized vis-a-vis theelectronic device being tested.

[0129] The present invention provides methods for manufacturing suchcontact devices for making connection to an electronic circuit deviceand methods of using the same in the production of integrated circuits,liquid crystal displays or other electronic devices. In accordance withthe present invention, the manufacturing of the contact device and theelectronic device is more tightly integrated, thereby enabling moreefficient manufacturing of the contact device, and thereby enabling moreeffective input by the electronic device designer/manufacturer intoproperties of the contact device, and smaller and more highly integratedelectronic devices.

[0130] For purposes of understanding the present invention, it should benoted that, as device and pin/bonding pad geometries and dimensions ofthe electronic device become increasingly finer, leading, for example,to finer pitches and spacings, the physical area or real estate,particularly near the probe tip/finger areas (particularly with astructure such as disclosed in U.S. Pat. No. 5,621,333) becomesincreasingly critical. It should be noted that the electronic devicedesigner/manufacturer must try to achieve the greatest density possible,which thus leads to the smallest possible devices and/or the smallestpossible pad spacings, which in turns controls the width of, andavailable area/real estate in, the probe tip/finger areas. In general,this trend has led to smaller probe tips/fingers, and finer conductorruns in these areas.

[0131] Unfortunately, however, this tends to compromise the contactdevice or probe performance in certain respects, as smaller conductorruns may lead to undesirable electrical characteristics. For example,conductor runs that are too narrow may result in increasedresistance/impedance or heating, or simply an inability to carry thedesired or required current level. Other leads, for example, may haveminimal current or signal performance requirements. Thus, it may bedesirable to have a wider conductor for power or ground leads, forexample, even if this results in smaller conductors for other leads. Italso may be desirable in certain applications to tailor the conductorruns for certain fingers to have a greater or lesser width, whileadjusting the widths of other conductors accordingly. Other conductors,for example, may have minimal or maximal conductor widths and/orspacings due to the characteristics of the signals to be carried on suchconductors. As physical area becomes more constrained, in general it canbecome important that conductors be arranged near the probe tip/fingerareas in ways (in terms of size, spacing, etc.), that optimize thedesired electrical characteristics.

[0132] In accordance with the present invention, such electronicdevices, including those with electrical or physical characteristics ofthe contact device conductors selected or optimized by the designer ormanufacturer of the electronic device, may be produced in a moreoptimized and efficient manner. It should be understood that the presentinvention is particularly well suited to produce contact devices orprobes such as is disclosed in U.S. Pat. No. 5,621,333 and for theproduction of electronic devices such as integrated circuits, liquidcrystal or other displays and other devices using contact devices havingelectrical contact points that are produced using photolithographic orother automated design and/or manufacturing techniques, although certaintechniques of the present invention may be extended to other types ofcontact or probe devices, such as those described above.

[0133] In accordance with the present invention, more automatedproduction of contact or probe devices, in whole or part, is implementedas part of the design process for the electronic device. In accordancewith the present invention, physical characteristics of the contactdevice, such as physical size or geometry and the location and size ofcontact points, are specified as part of the electronic devicedesign/manufacturing process. Through data entry or selection of contactdevice options presented to one or more designers of the electronicdevice, characteristics of the contact device are specified as part ofthe electronic device design/manufacturing process. Thereafter, datagenerated as part of the electronic device design/manufacturing processis provided to an automated tool for layout and/or manufacture of thecontact device.

[0134] More preferably, the designer of the electronic device has theoption to specify or select desired electrical characteristics ofparticular conductors on the contact device. In accordance with thepresent invention, the physical layout, including size, position and/orlength of the fingers or conductors of the contact device or probe, maybe more automatically generated. With probe or contact devices such asdisclosed in U.S. Pat. No. 5,621,333 and the like, such a process mayenable production of masks or patterns (such an electron beam or opticalwriting device) to generate the probe or contact device as a result ofsoftware processing of data generated by the electronic device designprocess. In particular, probes or contact devices having conductorcharacteristics, either physical or electrical, specified or selected bya designer of the electronic device may be more efficiently generated ina more automated manner, thereby enabling the ultimate manufacture ofthe electronic devices in a more efficient or optimized manner.

[0135] Referring to FIG. 26A, a general design flow in accordance withcertain preferred embodiments of the present invention is illustrated.At step 450, the device (e.g., integrated circuit, display or otherelectronic device having bonding pads or other conductor attachmentpoints, etc.) is designed at a high level, as indicated by the box HLD,for high level design. The HLD step may be conducted usingconventional-type electronic design tools. For example, at step 450 adesigner may define desired input and output characteristics of thedevice being designed, and may determine various transfer function,logic or other electrical or signal characteristics of the device. Forexample, such design may be accomplished using VHDL, behavioral modelsor other analog and/or digital design characteristics. As a part of suchHLD process, library 452 may be accessed. Library 452 may containvarious libraries of circuit elements, modules or other design data tofacilitate the HLD of the electronic device. In certain preferredembodiments, library 452 may contain or be able to access elementsspecifying physical or electrical characteristics or options availablefor contact points or conductor runs of the contact device.

[0136] Device fabrication is performed at step 454, it being understoodthat additional design verification steps may have occurred between step450 and step 454 as part of the overall electronic device designprocess. For example, high level designs typically undergo simulation,layout, re-simulation and other design verification steps in order todebug to the extent possible the design of the electronic device priorto expending the resources for device fabrication. All such design stepsare contemplated by the design flow of FIG. 26A. After devicefabrication step 454, the devices, typically in wafer form, proceed tostep 464 for probe testing.

[0137] A parallel design flow for contact device preparation isillustrated in FIG. 26A and is an important aspect of certain preferredembodiments of the present invention. As illustrated, the HLD designstep 450 also entails generation of data suitable for use indesign/fabricating the contact device. In certain preferred embodiments,at a HLD stage a designer may specify physical or electricalcharacteristics of the contact device. As illustrative examples, thedesigner may specify (or select, etc.) that certain contacts of theelectronic device are power supply lines, non-critical level sensitivelines (such as chip select or status lines), or high frequency orfrequency critical lines, etc. As certain contact devices ascontemplated by the present invention enable the conductors and contactsto be more precisely tailored for the particular desiredcharacteristics, having such characteristics selectable by a designer ata higher level point in the electronic device design cycle will enablemore automated design tools to, for example, layout and map theconductors of the contact device. As for example, high frequency linesmay be mapped to preserve a controlled impedance environment to a highdegree, while power supply and/or ground conductors may be arranged ormapped to provide a larger current carrying capacity. Non-critical linesmay be mapped in a less critical (e.g., smaller conductor form) mannerin order to minimize area usage in critical areas. In addition, certaindevices may specify an external impedance, such as a decouplingcapacitor at a point close to the contact pads of the contact device (asdescribed elsewhere herein). With such an automated design flow asillustrated in FIG. 26A, at a higher level point in the design cycledata specifying such an external impedance may be presented to tools forlaying out and mapping the conductors of the contact device.

[0138] At step 456, a tool for generating and/or processing test pad orother data specifying or identifying characteristics of the contactpoints of the electronic device is utilized. Such a step may entailextracting contact point physical or electrical characteristics datacorresponding to the electronic device, but preferably the tools of theHLD step for the electronic device present data specifying relevantdesired physical and/or electrical characteristics of the contactdevice. What is important is that such data for purposes of preparingthe contact device be made available, preferably in a more automatedmanner, to the design and fabrication flow for the contact device.

[0139] At step 458, a contact device tool lays out and/or mapsconductors of the contact device. Such a tool preferably contemplatesthe type of tester or testers to be used to test the electronic device,and also makes use of any physical and/or electrical data specified orselected by the HLD process for the electronic device. With such adesign flow, preparation of the contact device, including reflectingdesign data input from the electronic device design process, may be morereadily conducted. With such a design flow, particular conductors of thecontact device may be more readily tailored for the particular desiredphysical and/or electrical characteristics, preferably as specified orselected as part of the electronic device design process.

[0140] At step 460, based on data generated at step 458, the contactdevice is prepared. As illustrative examples, by way of steps 458 and460, a layout and mapping of the conductors of the contact device ismade, and photolithographic or similar masks are more automaticallyprepared or generated (such as by way of a mask shop) in order for thecontact device to be prepared (illustrative steps to prepare such acontact device are described elsewhere herein).

[0141] As previously described, certain preferred fabrication processesof the contact device involve laser cutting with a chuck prepared forthe laser cutting step. In an alternative design flow embodiment, datagenerated at step 458 for the contact device is more automaticallygenerated in a form suitable for preparation of the chuck. As previouslydescribed, a DXF or other suitable data format file may be created inorder to facilitate the machining or other preparation of a chuck orother implement for producing the contact device (e.g., a fine pitch,fine slit contact device, for which precise laser cutting is desired,etc.).

[0142] At step 460, the contact device is fabricated. At step 464, probetesting of the electronic devices may be accomplished, preferably at awafer, unpackaged level. Tested devices may be rejected and identifiedas rejected (such as by inking or tracking with a computer), andelectronic devices passing the probe testing step may proceed to devicepackaging step 466. At step 466, the wafers may be diced into chips, forexample, with chips encapsulated and packaged, such as with wirebonding, etc., and packaged in a resin or ceramic or other package.Thereafter, packaged devices may undergo additional testing at step 468,with the device either rejected or accepted. Accepted devices may thenbe prepared for use in a system design, prepared for inventorying,shipment, sales, etc.

[0143] Referring to FIG. 26B, exemplary data format 470 is illustrated.To facilitate the design flow depicted in FIG. 26B for the contactdevice, at step 450 and/or step 456 (or other suitable point in thecontact device design flow), electronically stored parameters for thecontact points of the contact device are generated and/or processed. Asillustrative examples, coordinate-type location data for particularcontact points may be provided, along with a unique identifier or namefor the pad or contact point. Preferably, pad or contact data isprovided, which may specify the type of signals to be transmittedthrough the pad (e.g., power supply or ground, high frequency signaltransmission, etc.) and/or other suitable data by which particularphysical or electrical characteristics of the contact point of thecontact device may be determined. Such pad data may be generated as aresult of a designer of the electronic device specifying or selectingoptions presented as a part or, or in conjunction with, HLD step 450.Still preferably, in certain embodiments tester channel or othersuitable data identifying channels or other characteristics of thetester to be used to test the electronic device is provided.

[0144] The format of FIG. 26B is exemplary only; what is important isthat the design flow of the electronic device contemplate the designflow of the contact device, and present data to the contact devicedesign flow in a suitable and more automated electronic format.Preferably, a person involved in the HLD process of the electronicdevice specify or select parameters of the contact device, so thatconductors of the contact device may be laid out or mapped based on thedesired physical and/or electrical characteristics of the particularconductors, which may include laying out the contact device so thatexternal impedances may be provided at a desirable point on the contactdevice (e.g., a decoupling capacitor or other external impedance at apoint close to which the contact device contacts the electronic device,etc.).

[0145] In accordance with such embodiments, improved processes formanufacturing electronic devices may be developed. For example, methodsin accordance with such embodiments may include the steps of: generatinga design description of the electronic device using a computer aideddesign tool; electronically determining physical device datarepresenting a physical description of the electronic device based onthe design description, wherein the physical device data includes datadefining connection points for connecting the electronic device toexternal circuits; producing a physical embodiment of the electronicdevice in accordance with the physical device data; electronicallydetermining physical test member data representing conductors andcontact points of a test member for testing the electronic device;producing the test member in accordance with the test member data;engaging the test member with the electronic device, wherein contactpoints of the test member engage connection points of the electronicdevice, wherein stimulus and response instruments apply test signals tothe electronic device through the test member and receive signals fromthe electronic device, wherein the stimulus and response instrumentsdetermine whether the electronic device is defective. Refinements ofsuch methods may include: the physical device data includes dataidentifying one or more connection points of the electronic device andalso includes signal data indicative of electrical signalcharacteristics of signals to be conducted through the one or moreconnection points; the step of electronically determining physical testmember data includes determining physical characteristics of conductorsof the test member in accordance with the signal data; the width of oneor more of the conductors is determined in accordance with the signaldata; the spacing of one or more of the conductors in determined inaccordance with the signal data; the width and spacing of one or more ofthe conductors is determined in accordance with the signal data; thephysical characteristics of a first conductor is determined at a firststep, wherein the physical characteristics of a second conductor isdetermined at a second step, wherein the physical characteristics of thesecond conductor are determined based on the signal data and/or thephysical characteristics of the first conductor; the first conductor isdetermined to have a first width, wherein the second conductor isdetermined to have a second width, wherein the first width is greaterthan the second width; the conductors include one or more thirdconductors, wherein the one or more third conductors are determined tohave a third width; the third width is intermediate to the first andsecond widths; the width and spacing of the conductors is determined inaccordance with the signal data, wherein the width and spacing of theconductors is determined in an iterative manner depending upon signaldata of one or more of the conductors; and/or the width and spacing ofthe conductors is physically mapped in accordance with the signal data.

[0146] Additional preferred embodiments of the present invention inwhich multiple electronic devices, or arrays of contacts on one or moreelectronic devices, may be simultaneously probed will be described withreference to FIGS. 27 and 28.

[0147]FIG. 27 illustrates an exemplary arrangement for such multi-siteor array probing in accordance with preferred embodiments of the presentinvention. In such embodiments, multiple probe members are provided; inthe illustrative embodiment, each side includes two probe members, lowerprobe member 482 and upper probe member 486, which may be manufacturingas described elsewhere herein. Each probe member includes a plurality ofcontact bumps 494 for contact to electronic devices formed on substrate480.

[0148] As previously described, position of a suitable mechanical groundor support is important for proper stress sharing and/or compliance withdeviations with planarity of the contact pads on the electronic devices.In the illustrative arrangement, first mechanical support 484 isprovided between lower probe member 482 and upper probe member 486.Preferably, mechanical support 484 is glued or otherwise secured in afixed manner to the two probe members. Mechanical support 484 providessupport for lower probe member 482 when it is pushed into contact withthe electronic devices. Mechanical support 488 is provided above upperprobe member 486 and is secured to an upper surface of upper probemember, again preferably with a glue or other adhesive in a fixedmanner. Mechanical support 488 is coupled to PCB 490, preferably in amanner to be adjusted for alignment purposes. A three point adjustmentor four point adjustment mechanism preferably is used to adjustprimarily the planarity of the contact device, and in particular theplanarity of the contacts of the probe member, with respect to thesurface of substrate 480. The conductor runs on probe members 482 and486 is electrically coupled to PCB 490 in the illustrated embodimentswith flex circuits 492 or other suitable electrical connectorarrangement.

[0149] In certain preferred embodiments, each of the probe members hasone, two or perhaps more contact pads per finger (as described elsewhereherein), and preferably has fingers arranged in a line so as to probemultiple electronic devices, or multiple rows of contacts on one moredevices (e.g., a type of array probing). The size and positioning andgeometries of the probe members and mechanical support 484, as well ascontact positions, may be selected so as to properly correspond withcontact pads on the electronic devices.

[0150] As an illustrative example, such a contact device configurationmay be used to probe an array of electronic devices on a wafer. Asillustrated in FIG. 28, wafer 500 includes a number of electronicdevices 502 arranged in a conventional matrix manner. Such devices maybe, for example, dynamic random access memories or other memory or othersemiconductor devices. In the illustrated arrangement, each electronicdevice 502 includes a single row of contact pads arranged down thecenter or in the interior of the electronic device (such as the LOCdevices described elsewhere herein). With the arrangement of FIG. 27,fingers on each of the probe members may span eight or some otherdesired number of electronic devices. With each probe member contactingone row of electronic devices, a four by eight array of electronicdevices may be simultaneously probed with the contact device.

[0151] As will be understood, other arrangements of electronic devicesmay be probed with such a configuration, such as a four by four or otherarray, and also it may be used to probe an array of contacts on a singleelectronic device, or an array of contacts on a row or other multiplearrangement of electronic devices, etc.

[0152] A further preferred embodiment of a contact device incorporatingexternal impedances or other components on the probe member will now bedescribed with reference to FIG. 29.

[0153] As illustrated in FIG. 29, probe member 506 includes a number offingers 508, which may be formed in a manner as described elsewhereherein. Conductor run 510 extends back from the tip portion of thefingers, and the conductor runs of probe member 506 are mapped to spreadout so that component 512 may be electrically coupled to conductor run510. Component 512 may be, for example, a decoupling capacitor with afirst end coupled to a power supply line, and with a second end coupledto the grounded substrate through via 511. As an additional example, theconductor runs may be mapped to provide an area for component 514 to beformed directly onto the substrate of the probe member. As an additionalexample, component 514 may be a planar capacitor formed with a thinnerdielectric formed between the grounded substrate and an upper plate ofthe capacitor. As one additional component, a short to the groundedsubstrate may be formed by via 516 at a position on or near one or moreof fingers 508.

[0154] Resistive or inductive elements may similarly be formed on probemember 506, with proper mapping of the conductor runs to provide asuitable area for the component, and proper fabrication steps. Certainsimple external circuits similarly may be formed on the probe members,such as a filter or other circuit as may be desired for the particularelectronic devices.

[0155] It will be appreciated that the invention is not restricted tothe particular embodiment that has been described, and that variationsmay be made therein without departing from the scope of the invention asdefined in the appended claims and equivalents thereof. For example,although the invention has been described with reference to the drawingsin terms of strip line and microstrip transmission line environments, ifthe film 14 were omitted and every other conductor run 26 across thecontact device were a ground conductor run, a combination of amicrostrip and coplanar transmission line environment would be provided.If every other conductor run were not a ground run, a microstriptransmission line environment would be provided as far as the forwardedge of the layer 44, and for some applications, it might be acceptablefor the transmission line environment to terminate at this point,provided that it is quite close to the contact bumps. Application of theinvention to a semiconductor tester has been described with reference toan implementation in which there is one contact bump on each finger ofthe contact device, and the use of individual fingers for each contactbump ensures maximum accommodation of non-coplanarity of the contactpads of the DUT. However, it might be advantageous to provide twocontact bumps, each connected to its own conductor run, since torsion ofthe finger accommodates a difference in height of the respective contactpads, and the greater width of the finger provides substantially greaterstiffness with respect to deflection. The invention is not limited totesting of devices prior to packaging and may he used for final testingof packaged devices, particularly a device that is packaged for surfacemounting, since the terminals are then suitably positioned forengagement by the contact bumps. Further, numerical references, whilegiving unexpectedly desirable results in the preferred embodiments overprior art techniques, may be adjusted in other embodiments.

[0156] Various embodiments are disclosed for illustrative purposes,which may be utilized to produce contact devices for testing a varietyof electronic devices, and for producing electronic devices utilizingsuch contact devices.

1. A method comprising the steps of: providing a substrate of a metalhaving a major portion and a tip portion projecting therefrom; adheringa dielectric material to the substrate; adhering a metal layer to thedielectric layer; selectively removing portions of the metal layer toform conductor runs extending over the tip portion, while leavingportions of the dielectric layer exposed between the conductor runs,wherein a multilayer composite structure is formed; and slitting the tipportion of the composite structure with a laser, wherein fingers areformed that project from the major portion of the composite structure incantilever fashion and each of which supports at least one conductorrun, wherein a contact device for use in establishing electricalconnection to an electronic device is formed, wherein the laser slittingis conducted with fiducials cut with the laser with the conductorsfacing towards the direction of the laser, wherein the fingers are cutwith the laser with the conductors facing away from the direction of thelaser.
 2. A method comprising the steps of: carrying out a devicemanufacturing process to produce a device having electrically-responsivecircuits; positioning the device on a positioning device; effectingaligned relative movement of the device with respect to a contact deviceto establish initial contact therebetween, wherein the contact deviceincludes contacts positioned in a contact region on fingers having alength extending away from a support area on a substrate and amechanical ground positioned between the contact region of the fingersand the support area, wherein the support area includes a controlledimpedance region for at least certain conductors coupled to certain ofthe contacts, and wherein the contact region includes a stubb region,wherein the certain conductors have a size and impedance different fromthe size and impedance of these conductors in the controlled impedanceregion; applying test signals to the device and electrically determiningwhether the device is defective; recording whether the device isdefective; removing the device from the positioning device; andpackaging and assembling the device if it is not defective.
 3. A probeapparatus for testing an electronic device having connection pointsthereon, comprising: a probe member having a proximal end and a distalend, wherein the probe member comprises a substrate having fingersprojecting from the distal end of the probe member along an axis,wherein the fingers have conductors formed thereon for connection withthe connection points of the electronic device, wherein one or more ofthe fingers include at least two contacts in a contact region forconnection to the electronic device, wherein the at least two contactsare arranged along the axis; and a support member mechanically coupledto the probe member; wherein the support member is coupled to the probemember so that the probe member has a mechanical ground positioned awayfrom the contact region of the fingers towards the proximal end.
 4. Amethod for manufacturing an electronic device, comprising the steps of:generating a design description of the electronic device using acomputer aided design tool; electronically determining physical devicedata representing a physical description of the electronic device basedon the design description, wherein the physical device data includesdata defining connection points for connecting the electronic device toexternal circuits; producing a physical embodiment of the electronicdevice in accordance with the physical device data; electronicallydetermining physical test member data representing conductors andcontact points of a test member for testing the electronic device;producing the test member in accordance with the test member data;engaging the test member with the electronic device, wherein contactpoints of the test member engage connection points of the electronicdevice, wherein stimulus and response instruments apply test signals tothe electronic device through the test member and receive signals fromthe electronic device, wherein the stimulus and response instrumentsdetermine whether the electronic device is defective.
 5. The method ofclaim 4, wherein the physical device data includes data identifying oneor more connection points of the electronic device and also includessignal data indicative of electrical signal characteristics of signalsto be conducted through the one or more connection points.
 6. The methodof claim 5, wherein the step of electronically determining physical testmember data includes determining physical characteristics of conductorsof the test member in accordance with the signal data.
 7. The method ofclaim 6, wherein the width of one or more of the conductors isdetermined in accordance with the signal data.
 8. The method of claim 6,wherein the spacing of one or more of the conductors in determined inaccordance with the signal data.
 9. The method of claim 6, wherein thewidth and spacing of one or more of the conductors is determined inaccordance with the signal data.
 10. The method of claim 6, wherein thephysical characteristics of a first conductor is determined at a firststep, wherein the physical characteristics of a second conductor isdetermined at a second step, wherein the physical characteristics of thesecond conductor are determined based on the signal data and/or thephysical characteristics of the first conductor.
 11. The method of claim10, wherein the first conductor is determined to have a first width,wherein the second conductor is determined to have a second width,wherein the first width is greater than the second width.
 12. The methodof claim 11, wherein the conductors include one or more thirdconductors, wherein the one or more third conductors are determined tohave a third width.
 13. The method of claim 12, wherein the third widthis intermediate to the first and second widths.
 14. The method of claim6, wherein the width and spacing of the conductors is determined inaccordance with the signal data, wherein the width and spacing of theconductors is determined in an iterative manner depending upon signaldata of one or more of the conductors.
 15. The method of claim 6,wherein the width and spacing of the conductors is physically mapped inaccordance with the signal data.